JP2006343443A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption for a display device in which display is performed by moving liquid between electrodes. <P>SOLUTION: When a voltage is applied to a mesh texture front side electrode 6 and a mesh texture rear side electrode 7 which are provided on a front face and a rear face of electro-osmosis membrane 5 in a first condition, by upward driving force by potential difference arising between the front face side and the rear face side of the electro-osmosis membrane 5, the liquid 9 in a rear face side space 4b moves into a front face side space 4a via the rear face side electrode 7, the electro-osmosis membrane 5 and the front face side electrode 6, so as to turn to a display state based on a color of the liquid 9. On the other hand, when the voltage is applied to the front face side electrode 6 and the rear face side electrode 7 in a second condition, by downward driving force by the potential difference arising between the front face side and the rear face side of the electro-osmosis membrane 5, the liquid 9 in the front face side space 4a moves into the rear face side space 4b via the front face side electrode 6, the electro-osmosis membrane 5 and the rear face side electrode 7, so as to turn to a display state based on a color of the front face side electrode 6. In either case, even if applying voltage to each electrode of 6 and 7 is stopped, the upward or downward driving force by the potential difference is only lost and the display state is maintained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device that performs display by moving a liquid between electrodes.

  In a conventional display device that performs display by moving liquid between electrodes, a colored liquid (dielectric material) and bubbles are sealed in a container constituting one pixel, and are provided opposite to each other on the outer surface of one side of the container. When a voltage is applied to the pair of first electrodes, the colored liquid is moved to one side in the container by an electrostatic force, and the bubbles are moved to the other side in the container. When a voltage is applied to the pair of second electrodes provided opposite to each other, the electrostatic force moves the colored liquid to the other side in the container and moves the bubbles to one side in the container. There is one in which display is performed by making visible pixels on only one side of the container (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 8-254962

  By the way, in the conventional display device described above, for example, a voltage is applied to the pair of first electrodes on one side of the container, the colored liquid is moved to one side in the container by electrostatic force, and the bubbles are moved into the container. In the state of moving to the other side and displaying the color of the colored liquid itself, if the voltage application to the pair of first electrodes is stopped, the electrostatic force disappears, so the colored liquid is moved to one side in the container. The moved state cannot be maintained, and the colored liquid moves freely toward the other side in the container, and the color display state due to the color of the colored liquid itself is lost. Therefore, in order to maintain the color display state (and white display state) by the color of the colored liquid itself, it is necessary to continue to apply a voltage to the pair of first electrodes (and the pair of second electrodes). There is a problem that electric power becomes large.

  Therefore, an object of the present invention is to provide a display device that can reduce power consumption.

  In order to achieve the above object, according to the present invention, in a display device, a space constituting one pixel surrounded by a front surface side substrate, a back surface side substrate, and a side wall provided therebetween, and the front surface side substrate in the space And an electric osmosis membrane that separates the space into a front-side space and a back-side space, and a dielectric encapsulated in a part of the front-side space and the back-side space. It is provided with the liquid and the surface side electrode and back surface side electrode which are provided in the surface and back surface of the said electroosmosis membrane, and control the passage of the said liquid.

  According to the present invention, a voltage is applied to the front surface side electrode and the back surface side electrode, and the surface is passed through the electroosmotic membrane by a downward or upward driving force due to a potential difference generated between the front surface side and the back surface side of the electroosmotic membrane. After the liquid in the side space or the back side space is moved to the back side space or the front side space and the display is switched, Only the downward or upward driving force due to the potential difference generated between the front and back sides of the osmotic membrane disappears, and the switched display state can be maintained. Therefore, power consumption can be reduced.

(First embodiment)
FIG. 1 is a sectional view showing a white display state of one pixel portion of a display device as a first embodiment of the present invention. This display device includes a flat rectangular front surface side transparent plate (substrate) 1 and a back surface side (transparent) plate (substrate) 2 made of a colorless and transparent material such as glass or resin. In the case of a reflective display device or the like visually recognized from the front side transparent plate 1 side, the back side (transparent) plate 2 does not necessarily need to be colorless and transparent.

  The front surface side transparent plate 1 and the back surface side (transparent) plate 2 are disposed to face each other, and a side wall 3 (a front surface side wall 3a and a back surface side wall 3b) is provided between them. A space 4 that constitutes one pixel is formed by a space surrounded by the front surface side transparent plate 1, the back surface side (transparent) plate 2, and the side wall 3.

  In the space 4, an electroosmotic membrane 5 is provided at a central portion between the front surface side transparent plate 1 and the back surface side (transparent) plate 2. The electroosmotic membrane 5 is formed by arranging a large number of strands in which a plurality of silica fibers are twisted into a tube 5a made of extremely thin silica (not shown, hereinafter referred to as silica yarn) is inserted, It has a structure filled with a filler (or adhesive (not shown)) made of silicone rubber or the like.

  In this case, the length and diameter of the silica yarn are substantially the same as the length and inner diameter of the tube 5a. Further, the total cross-sectional area of the plurality of silica fibers constituting the silica yarn is about half of the cross-sectional area in the tube 5a, so that liquid can pass through the tube 5a. The tube 5a is made of silica, that is, an acidic active material, and has a function of positively charging a liquid in contact with the inner wall surface. In this case, however, only an extremely thin layer of liquid that comes into contact with the inner wall surface of the tube 5a is positively charged. Thus, the silica yarn is for positively charging more liquid that comes into contact with each silica fiber.

  A front-side electrode 6 and a back-side electrode 7 are provided on the front and back surfaces of the electroosmotic membrane 5. In this case, the front surface side electrode 6 and the back surface side electrode 7 have a net shape to allow the passage of liquid. In particular, the surface-side electrode 6 is made of a white conductive material, or a surface of a copper wire or the like provided with a white coating.

  Here, the space 4 is separated into the front surface side space 4 a and the back surface side space 4 b by the electroosmotic membrane 5. That is, the surface side space 4a is formed by the space surrounded by the surface side transparent plate 1, the electroosmotic membrane 5 and the surface side wall 3a, and is surrounded by the back side (transparent) plate 2, the electroosmotic membrane 5 and the back side wall 3b. The back space 4b is formed by the space formed. In this case, the volume of the front surface side space 4a and the volume of the back surface side space 4b are substantially the same. That is, the distance between the front surface side transparent plate 1 and the electroosmotic membrane 5 and the distance between the back surface side (transparent) plate 2 and the electroosmotic membrane 5 are substantially the same.

  On the left side of FIG. 1 in the portion where the electroosmotic membrane 5 is provided, a slit-like air hole 8 that communicates both the spaces 4a and 4b is provided. In the white display state to be described later shown in FIG. 1, a liquid made of a liquid dielectric such as a black methanol solution in a region corresponding to the electroosmotic membrane 5 other than the region corresponding to the vent hole 8 in the back surface side space 4 b. 9 is enclosed, and air is enclosed in the region corresponding to the vent hole 8 in the back surface side space 4b, the vent hole 8, and the front surface side space 4a. In this case, the end surface of the liquid 9 sealed in the back surface side space 4b on the side of the vent hole 8 is dented with a meniscus formed by surface tension.

  Next, the display operation of this display device will be described. In the state shown in FIG. 1, a voltage is applied to both electrodes 6 and 7 under the first condition, that is, a negative voltage is applied to the front electrode 6 and a positive voltage is applied to the back electrode 7. Then, the liquid 9 in the back surface side space 4b causes the reticulated back surface side electrode 7, the electro osmotic membrane 5 and the reticulated surface by the upward driving force due to the potential difference generated between the front surface side and the back surface side of the electroosmotic membrane 5. It starts to move into the surface side space 4a through the side electrode 6.

  In this case, first, as shown in FIG. 2, the amount of the liquid 9 in the back surface side space 4b is reduced to some extent, and the recessed end surface of the liquid 9 in the back surface side space 4b is moved to the right side to some extent. Accordingly, when the liquid 9 in the back surface side space 4b moves to some extent above the gap including the mesh-like front surface side electrode 6, the liquid 9 is moved to the right side of the front side wall 3a due to the surface energy. And the inner surface on both sides in the direction perpendicular to the paper surface (except for the inner surface in the vicinity of the vent hole 8), and further spread on the inner surface of the surface-side substrate 1 adjacent thereto.

  Next, as shown in FIG. 3, the amount of the liquid 9 in the back side space 4b is further reduced, and the recessed end surface on the vent hole 8 side of the liquid 9 in the back side space 4b is further moved to the right side. Accordingly, when the liquid 9 in the back surface side space 4b further moves into the front surface side space 4a, the liquid 9 wets and spreads on the inner surface of the front surface side substrate 1, and the right side portion in the front surface side space 4a. The liquid 9 is filled, and an end face that is recessed toward the vent hole 8 side of the filled liquid 9 is formed.

  Then, further through the state shown in FIG. 4, finally, as shown in FIG. 5, the area other than the region corresponding to the vent hole 8 in the surface-side space 4a, that is, the electric energy, as shown in FIG. The entire region corresponding to the osmotic membrane 5 is filled with the liquid 9, and the end surface of the filled liquid 9 on the side of the vent hole 8 is recessed. The air in the front surface side space 4a moves into the back surface side space 4b through the vent hole 8 in accordance with the movement of the liquid 9 from the back surface side space 4b to the front surface side space 4a.

  On the other hand, in the state shown in FIG. 5, a voltage is applied to both the electrodes 6 and 7 under the second condition, that is, a positive voltage is applied to the front electrode 6 and a negative voltage is applied to the back electrode 7. When applied, the liquid 9 in the surface-side space 4a is made to have a mesh-like surface-side electrode 6, electro-osmotic membrane 5 and mesh-like by a downward driving force due to a potential difference generated between the surface side and the back side of the electro-osmotic membrane 5. Begins to move into the back surface side space 4b through the back surface side electrode 7.

  In this case, first, as shown in FIG. 6, the amount of the liquid 9 in the surface side space 4a is reduced to some extent, and the recessed end surface of the liquid 9 in the surface side space 4a is moved to the right side to some extent. Accordingly, when the liquid 9 in the front surface side space 4a moves to a lower side including the gap between the net-like back surface side electrodes 7 to some extent, the liquid 9 is transferred to the back side wall 3b due to the surface energy. It wets and spreads on the inner surface on the right side and the inner surfaces on both sides in the vertical direction of the paper (except for the inner surface in the vicinity of the vent hole 8), and further spreads on the inner surface of the back side substrate 2 adjacent thereto.

  Next, as shown in FIG. 7, the amount of the liquid 9 in the surface side space 4a is further reduced, and the recessed end surface on the vent hole 8 side of the liquid 9 in the surface side space 4a is further moved to the right side, Accordingly, when the liquid 9 in the front surface side space 4a further moves into the back surface side space 4b, the liquid 9 wets and spreads on the inner surface of the back surface side substrate 2, and the right side portion in the back surface side space 4b. The liquid 9 is filled, and an end face that is recessed toward the vent hole 8 side of the filled liquid 9 is formed.

  Further, through the state as shown in FIG. 8, finally, as shown in FIG. 1, in addition to the region corresponding to the vent hole 8 in the back surface side space 4b, in other words, as shown in FIG. The entire region corresponding to the osmotic membrane 5 is filled with the liquid 9, and the end surface of the filled liquid 9 on the side of the vent hole 8 is recessed. In addition, the air in the back surface side space 4b moves into the front surface side space 4a through the vent hole 8 according to the movement of the liquid 9 from the inside of the front surface side space 4a to the back surface side space 4b.

  Next, the display state in the state shown in FIGS. 1 and 5 will be described. In the state shown in FIG. 1, external light incident from the surface side of the surface side transparent plate 1 is transmitted through the surface side transparent plate 1. Reflected by the white surface side electrode 6, this reflected light is emitted to the surface side of the surface side transparent plate 1 through an optical path opposite to the above, and white display is performed. On the other hand, in the state shown in FIG. 5, external light incident from the front surface side of the front surface side transparent plate 1 passes through the front surface side transparent plate 1 and is absorbed by the black liquid 9, resulting in a black display.

  By the way, in this display device, once the liquid 9 is moved into the front surface side space 4a or the back surface side space 4b, it is not necessary to apply a voltage to the electrodes 6 and 7 in order to maintain the state. That is, for example, when the applied voltage to each of the electrodes 6 and 7 is set to the same potential (for example, 0 V), or when the application of the voltage is stopped (open), the front side and the back side of the electroosmotic membrane 5 The upward or downward driving force due to the potential difference generated between the liquid 9 and the liquid 9 that has finished moving in the front surface side space 4a or the back surface side space 4b remains in the space, and the display state is changed. Can be maintained. Therefore, in this display device, it is not necessary to apply power unless the display contents are changed, and power consumption can be reduced. Also, when a methanol solution is used as the liquid 9, electrolysis is less likely to occur than an aqueous solution even at a high voltage, which is preferable.

(Second Embodiment)
FIG. 9 is a sectional view showing a white display state of one pixel portion of a display device as a second embodiment of the present invention. This display device is different from the display device shown in FIG. 1 in that fine uneven surfaces 1a are formed on the inner surface of the surface-side transparent plate 1 by sandblasting or microblasting. In this case, the surface side electrode 6 does not need to be white.

  Then, as shown in FIG. 9, in a state where the liquid 9 is filled in a predetermined location in the back surface side space 4 b, external light incident from the front surface side of the front surface side transparent plate 1 passes through the front surface side transparent plate 1. Then, the light is scattered and reflected at the interface between the uneven surface 4 of the surface-side transparent plate 1 and the air in the surface-side space 4a, and this scattered reflected light is emitted to the surface side of the surface-side transparent plate 1 through an optical path opposite to the above. Is displayed in white. On the other hand, as shown in FIG. 10, in the state where the black liquid 9 is filled in a predetermined portion in the surface side space 4a, the scattering reflection on the uneven surface 4 of the surface side transparent plate 1 does not occur, and the surface side transparent External light incident from the surface side of the plate 1 is transmitted through the surface-side transparent plate 1 and absorbed by the black liquid 9, resulting in a black display.

(Other embodiments)
In the first embodiment, the color of the surface side electrode 6 and the color of the liquid 9 may be different from each other. For example, the surface side electrode 6 may be black, blue, red, and the liquid 9 may be white. . In this case, in the state shown in FIG. 1, the color display by the color of the surface side electrode 6 is performed, and in the state shown in FIG.

  In the second embodiment, the liquid 9 may be colorless and transparent methanol or a methanol solution, and the front electrode 6 may be black, blue, red, or the like. In this case, in the state shown in FIG. 9, white display is obtained due to scattering reflection on the uneven surface 1 a, and in the state shown in FIG. 10, scattering reflection on the uneven surface 1 a does not occur, and color display by the color of the surface side electrode 6 is performed. It becomes.

  Further, in each of the embodiments described above, the front side electrode 6 and the back side electrode 7 have been described as being net-like, but it is sufficient that the liquid is partially allowed to pass through, for example, a strip having a slit. It may be arranged in a shape.

Sectional drawing which shows the white display state of 1 pixel part of the display apparatus as 1st Embodiment of this invention. Sectional drawing shown in order to demonstrate the initial operation | movement at the time of applying a voltage on the both conditions of the display apparatus shown in FIG. 1 on 1st conditions. Sectional drawing shown in order to demonstrate the operation | movement following FIG. Sectional drawing shown in order to demonstrate the operation | movement following FIG. Sectional drawing which shows the black display state of the display apparatus shown in FIG. Sectional drawing shown in order to demonstrate the initial operation | movement at the time of applying a voltage on 2nd conditions to both electrodes of the display apparatus shown in FIG. Sectional drawing shown in order to demonstrate the operation | movement following FIG. Sectional drawing shown in order to demonstrate the operation | movement following FIG. Sectional drawing which shows the white display state of 1 pixel part of the display apparatus as 2nd Embodiment of this invention. Sectional drawing which shows the black display state of the display apparatus shown in FIG.

Explanation of symbols

1 Surface side transparent plate (substrate)
1a Uneven surface 2 Back side (transparent) plate (substrate)
DESCRIPTION OF SYMBOLS 3 Side wall 3a Front side wall 3b Back side wall 4 Space 4a Front side space 4b Back side space 5 Electroosmosis membrane 5a Tube 6 Front side electrode 7 Back side electrode 8 Vent 9 Liquid

Claims (5)

A space constituting one pixel surrounded by a front surface side substrate, a back surface side substrate, and a side wall provided therebetween;
An electroosmotic membrane provided between the front surface side substrate and the back surface side substrate in the space, and separating the space into a front surface side space and a back surface side space;
A liquid sealed in a part of the front side space and the back side space;
Provided on the front and back surfaces of the electroosmotic membrane, the front surface side electrode and the back surface side electrode for controlling the passage of the liquid,
A display device comprising:   The display device according to claim 1, wherein the front surface side electrode and the back surface side electrode have a net shape.   The display device according to claim 1, wherein the electroosmotic membrane is formed by arranging a large number of yarns inserted into a tube.   2. The display device according to claim 1, wherein a portion provided with the electroosmotic membrane is provided with a vent hole that connects the front surface side space and the rear surface side space.   The display device according to claim 1, wherein an inner surface of the surface-side substrate is provided with a surface that scatters and reflects light when not in contact with the liquid and transmits light when in contact with the liquid. A display device.

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